The Genitourinary System Flashcards
(44 cards)
What is the kidney?
Why do we need it?
The central regulator of homeostasis
Take in more water and salt than we need as we do not know how much we will need in a given day (e.g. hot or cold day, amount of exercise, etc.). This means the excess must be excreted (e.g. as urea)
Out of Na+, K+, H2O and urea - which of these do not have a pump?
H2O and urea
We have evolved acutally pumps for the ions
What are the 5 main functions of the kidney?
Excretion of metabolic products - urea, uric acid, creatinine
Excretion of foreign substances - drugs
Regulation of body fluids, electrolytes and acid-base balance
Control BP
Secrete hormones - erthropoietin, renin
What is the anatomical structure of the kidneys? Fill in the missing labels below:
Cortex = outer layer
Medullary region = inside the cortex
Renal artery = blood in
Renal vein = blood out
Ureter = urine out
What are the different blood vessels in the renal blood supply, starting from the renal artery, through the glomerular capillaries to the renal vein? Fill in the flow diagram below:
Describe the order of blood flow in the kidney
Renal artery
Segemental artery
Interlobar artery
Arcuate artery
Interlobular arterty
Afferent areteriole
Glomerular capillaries
Efferent arteriole
Peritubular capilaries
Interlobular vein
Arcuate vein
Interloar vein
Renal vein
What is the function of the bladder and urethra? How do they work together and urine fills the bladder?
The kidney eventually produces urine, which travels down the ureter to the bladder
The bladder fills to a particular volume (around 200ml) - and then is detected by the detrusor muscle and trigonal region
What are the functions of the:
detrusor muscle
trigone
internal sphincter
external sphincter
bulbourethral gland
Detrusor muscle = contracts to build pressure in the bladder to support urination
Trigone = stretching in this region signals to the brain for the need of urination
Internal sphincter = involuntary control to prevent urination
External sphincter = voluntary control to prevent urination
Bulbourethral gland = produces thick lubricant that is added to watery semen to promote sperm survival
What is the structure of a functional unit (nephron) in the kidney? Fill in the missing labels on the diagram below:
What is the function of the nephron at the start, during the PCT?
As solutes are pumped out of the filtrate / reabsorbed
the glomerular filtrate has a lower osmolarity
So water follows and moves out as well
Around the same amount of solute and water are reabsorbed
What are some key properties of the epithelial cells to support this function?
Many mitochondria - provides ATP for all the pumps (to pump out the solutes)
Drives Na/K ATPase
What is the function of the Loop of Henle?
Counter current system
Pump salt out at the top (thick ascending limb)
Generates salt gradient
Water comes out on thin descending limb (passive)
How are the epithelial cells of the loop of henle adapted to its functions?
Epithelial cells contain many mitochondria in the thick ascending limb of the loop of henle to provide ATP for the pumping activity
Epithelial cells of the thin decending loop of henle = passive movement of water = low mitochondria density as less ATP is needed
How can the amount of water reabsorption be varied in the DCT / CD?
Vary water reabsorption in the CD via vasopressin and aquaporins - it also changes the osmolarity surrounding the loop of Henle affecting the concentration gradient for reabsorption of water
What are the properties of the cells found in the DCT and CD?
What are the 2 cell types in the CD and their properties?
Epithelial cells of the DCT = rich in mitochondria
Principal cells = low mitohondrial density; Intercalated cells = rich in mitochondria
What are the 2 types of nephron?
What are the 3 depths of the nephron?
Which is more abundant that the other?
- Superfiial nephron; 2. Juxtamedullary nephron
- Cortex; 2. Outer medulla; 3. Inner medulla
10: 1 ratio for superficial to juxtamedullary
Why is the cortex of the kidney granular looking, whereas the medulla of the kidney is striated looking?
Where is the glomerulus found in comparison to the rest of the nephron?
All the glomerulae are found in the cortex (not organised into a pattern); all the Loops of Henle are found in the medulla
Almost always found near the early DCT
What does GFR stand for? How is GFR regulated?
What is the juxtaglomerular apparatus? What is its function?
Glomerular filtration rate - regulated by controlling how much liquid is coming into the glomerulus and renin production
It is located next to the glomerulus, between the afferent arteriole and the distal convoluted tubule of the same nephron. It is responsible for regulating GFR
What are the 3 types of cells found in the juxtaglomerular apparatus?
- Macula densa (found in the DCT) = regulates GFR through the tubulo-glomerular feedback mechanism;
- extraglomerular mesangial cells;
- juxtaglomerular cells = produce renin to regulate BP
How does glomerular filtration work?
What are the different processes that can occur within the nephron?
A passive process where fluid is driven through the glomerular capillaries into the Bowman’s capsule due to the hydrostatic pressure of the heart, which pushes small enough molecules through the semipermable membrane of the glomerular capillaries
It is impermeable to cells and proteins
Endothelium wiht fenstrations
Basement membrane
Podocytes with slits
Glomerular filtration, reabsorption, secretion, excretion - different substances undergo these processes in different amounts
What is meant by the terms hydrostatic and oncotic pressures?
How do these 2 pressures interact in the glomerulus?
In the glomerulus:
Hydrostatic pressure = fluid exerts this pressure (pressure comes from BP / heart contracting) so solutes and fluid are pushed out into the glomerular filtrate
Oncotic pressure = cells and protein are left behind in the glomerulus, creating an osmotic gradient, drawing the fluid back across the semi-permeable membrane
What is HPgc?
What is HPbw?
What is πgc?
So what is the equation to calculate Puf (filtration pressure)?
HPgc = hydrostatic pressure in the glomerular capillaries - drives fluid into the glomerular filtrate
HPbw = hydrostatic pressure in the bowman’s capsule - pulls fluid back into the glomerulus (HPgc works against this)
πgc = oncotic pressure of plasma proteins in the glomerular capillaries - pulls fluid back into the glomerulus
Puf = HPgc - HPbw - πgc
What is GFR?
How is GFR calculated?
Amount of fluid filtered from all the glomeruli into the bowman’s capsule in the kidneys per unit time (mL/min) - sum of filtration rate of all functioning nephrons
GFR = Puf x Kf
Where Puf = filtration pressure, and Kf = ultrafiltration co-efficient taking into account membrane permeability and surface area available for filtration
What are the 3 main factors that can be altered to affect / change GFR?
What are healthy GFRs in males and females respectively?
What occurs with GFR in renal disease?
Change in surface area, permeability or pressure
Males = 90-140mL/min; Females = 80-125mL/min
GFR falls - things that should be excreted via the kidneys remain in the plasma and build up over time
